Auditory false perceptions are mediated by psychosis risk factors

Introduction. Auditory hallucinations exist in psychotic disorders as well as the general population. Proneness to hallucinations, as measured by positive schizotypy, predicts false perceptions during an auditory signal detection task (Barkus, Stirling, Hopkins, McKie, & Lewis, 2007). Our aim was to replicate this result and extend it by examining effects of age and sex, both important demographic predictors of psychosis.

Method. A sample of 76 healthy volunteers split into 15-17 years (n = 46) and 19 years plus (n = 30) underwent a signal detection task designed to detect propensity towards false perceptions under ambiguous auditory conditions. Scores on the Unusual Experiences subscale (UE) of the O-LIFE schizotypy scale, IQ, and a measure of working memory were also assessed.

Results. We replicated our initial finding (Barkus et al., 2007): High scores on positive schizotypy were associated with false perceptions. Younger participants who scored highly on positive schizotypy reported significantly more false perceptions compared to other groups (p = .04). Older participants who had had an imaginary friend reported more false perceptions during the signal detection task (p <. 01).

Conclusions. Younger participants seem most vulnerable to the effects of positive schizotypal traits in terms of a signal detection deficit that underlies auditory hallucinations. Schizotypy may have greatest impact closer to the risk period for development of psychotic disorders.

Immunohistochemical study of pig retinal development

PURPOSE: The pig eye is similar to the human eye in terms of anatomy, vasculature, and photoreceptor distribution, and therefore provides an attractive animal model for research into retinal disease. The purpose of this study was to characterize retinal histology in the developing and mature pig retina using antibodies to well established retinal cell markers commonly used in rodents.

METHODS: Eyes were enucleated from fetuses in the 9th week of gestation, 1 week old piglets and 6 months old adult animals. Eyeglobes were fixed and cryosectioned. A panel of antibodies to well established retinal markers was employed for immunohistochemistry. Fluorescently labeled secondary antibodies were used for signal detection, and images were acquired by confocal microscopy. Mouse retina at postnatal day (P) 5 was used as a reference for this study to compare progression of histogenesis. Most of the primary antibodies have previously been used on mouse tissue.

RESULTS: Most of the studied markers were detected in midgestation pig retina, and the majority had a similar distribution in pig as in P5 mouse retina. However, rhodopsin immunolabeling was detected in pig retina at midgestation but not in P5 mouse retina. Contrary to findings in all rodents, horizontal cells were Islet1-positive and cones were calbindin-immunoreactive in pig retina, as has also been shown for the primate retina. Recoverin and rhodopsin immunolabeling revealed an increase in the length of photoreceptor segments in 6 months, compared to 1 week old animals.

CONCLUSIONS: Comparison with the published data on human retina revealed similar marker distribution and histogenesis progression in the pig and human retina, supporting the pig as a valuable animal model for studies on retinal disease and repair. Furthermore, this study provides information about the dynamics of retinal histogenesis in the pig and validates a panel of antibodies that reliably detects developing and mature retinal cell phenotypes in the pig retina.

Sparse multi-carrier index keying OFDM with index separation over correlated sub-carriers

In this paper, we propose a sparse multi-carrier index keying (MCIK) method for orthogonal frequency division multiplexing (OFDM) system, which uses the indices of sparse sub-carriers to transmit the data, and improve the performance
of signal detection in highly correlated sub-carriers. Although a receiver is able to exploit a power gain with precoding in OFDM, the sensitivity of the signal detection is usually high as the orthogonality is not retained in highly dispersive
environments. To overcome this, we focus on developing the trade-off between the sparsity of the MCIK, correlation, and performances, analyzing the average probability of the error propagation imposed by incorrect index detection over highly correlated sub-carriers. In asymptotic cases, we are able to see how sparsity of MCIK should be designed in order to perform superior to the classical OFDM system. Based on this feature, sparse MCIK based OFDM is a better choice for low detection errors in highly correlated sub-carriers.

Tributyltin (TBT) resistance in Aeromonas molluscorum Av27

O tributilestanho (TBT) é considerado um dos xenobióticos mais tóxicos, produzidos e deliberadamente introduzidos no meio ambiente pelo Homem. Tem sido usado numa variedade de processos industriais e subsequentemente descarregado no meio ambiente. O tempo de meia-vida do TBT em águas marinhas é de várias semanas, mas em condições de anóxia nos sedimentos, pode ser de vários anos, devido à sua degradação mais lenta. Embora o TBT tenha sido descrito como sendo tóxico para eucariotas e procariotas, muitas bactérias podem ser resistentes a este composto. O presente trabalho teve como objetivo principal elucidar o mecanismo de resistência ao TBT em bactérias. Para além disso, pretendeu-se desenvolver um biorepórter para detectar TBT no ambiente. Para atingir estes objetivos foram delineadas várias tarefas cujos principais resultados obtidos se apresentam a seguir. Várias bactérias resistentes ao TBT foram isoladas de sedimento e água do Porto de Pesca Longínqua (PPL) na Ria de Aveiro, Portugal. Entre estas, Aeromonas molluscorum Av27 foi selecionada devido à sua elevada resistência a este composto (concentrações até 3 mM), à sua capacidade de degradar o TBT em compostos menos tóxicos (dibutilestanho, DBT e monobutilestanho, MBT) e também por usar o TBT como fonte de carbono. A. molluscorum Av27 foi caracterizada genotipica e fenotipicamente. Os fatores de virulência estudados mostraram que esta estirpe i) possui atividade lipolítica; ii) não é citotóxica para células de mamíferos, nomeadamente para células Vero; iii) não possui integrões de classe I e II e iv) possui cinco plasmídeos com aproximadamente 4 kb, 7 kb, 10 kb, 100 kb e mais de 100 kb. Estes resultados mostraram que a estirpe Av27 não é tóxica, aumentando assim o interesse nesta bactéria para futuras aplicações, nomeadamente na bioremediação. Os testes de toxicidade ao TBT mostraram que este composto tem um impacto negativo no crescimento desta estirpe, bem como, na densidade, no tamanho e na atividade metabólica das células e é responsável pela formação de agregados celulares. Assim, o TBT mostrou ser bastante tóxico para as bactérias interferindo com a atividade celular geral. O gene Av27-sugE, que codifica a proteína SugE pertencente à família das “small multidrug resistance proteins” (SMR), foi identificado como estando envolvido na resistência ao TBT nesta estirpe. Este gene mostrou ser sobreexpresso quando as células crescem na presença de TBT. O promotor do gene Av27-sugE foi utilizado para construir um bioreporter para detetar TBT, contendo o gene da luciferase do pirilampo como gene repórter. O biorepórter obtido reúne as características mais importantes de um bom biorepórter: sensibilidade (intervalo de limite de detecção de 1-1000 nM), rapidez (3 h são suficientes para a deteção de sinal) e, possivelmente, não é invasivo (pois foi construído numa bactéria ambiental). Usando sedimento recolhido no Porto de Pesca Longínqua da Ria de Aveiro, foi preparada uma experiência de microcosmos com o intuito de avaliar a capacidade de Av27 para bioremediar o TBT, isoladamente ou em associação com a comunidade bacteriana indígena. A análise das amostras de microcosmos por PCR-DGGE e de bibliotecas de 16S rDNA revelaram que a comunidade bacteriana é relativamente estável ao longo do tempo, mesmo quando Av27 é inoculada no sedimento. Para além disso, o sedimento estuarino demonstrou ser dominado por bactérias pertencentes ao filo Proteobacteria (sendo mais abundante as Delta e Gammaproteobacteria) e Bacteroidetes. Ainda, cerca de 13% dos clones bacterianos não revelaram nenhuma semelhança com qualquer dos filos já definidos e quase 100% afiliou com bactérias não cultiváveis do sedimento. No momento da conclusão desta tese, os resultados da análise química de compostos organoestânicos não estavam disponíveis, e por essa razão não foi possível tirar quaisquer conclusões sobre a capacidade desta bactéria remediar o TBT em sedimentos. Esses resultados irão ajudar a esclarecer o papel de A. molluscorum Av27 na remediação de TBT. Recentemente, a capacidade da estirpe Av27 remediar solo contaminado com TBT foi confirmada em bioensaios realizados com plantas, Brassica rapa e Triticum aestivum (Silva 2011a), e também com invertebrados Porcellionides pruinosus (Silva 2011B). Assim, poder-se-á esperar que a bioremediação do sedimento na experiência de microcosmos também tenha ocorrido. No entanto, só a análise química dos compostos organostânicos deverá ser conclusiva. Devido à dificuldade em realizar a análise analítica de organoestânicos, um método de bioensaio fácil, rápido e barato foi adaptado para avaliar a toxicidade do TBT em laboratório, antes de se proceder à análise química das amostras. O método provou a sua utilidade, embora tenha mostrado pouca sensibilidade quando se usam concentrações de TBT baixas. Em geral, os resultados obtidos contribuíram para um melhor entendimento do mecanismo de resistência ao TBT em bactérias e mostraram o potencial biotecnológico de A. molluscorum Av27, nomeadamente, no que refere à sua possível aplicação na descontaminação de TBT no ambiente e também no desenvolvimento de biorepórteres.

Implementação de WDM com 4 canais no espetro do visível

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia de Electrónica e Telecomunicações

Sistema WDM de 4 canais

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia de Electrónica e Telecomunicações

Vigilância activa de eventos após vacinação

A vigilância de efeitos indesejáveis após a vacinação é complexa. Existem vários actores de confundimento que podem dar origem a associações espúrias, meramente temporais mas que podem provocar uma percepção do risco alterada e uma consequente desconfiança generalizada acerca do uso das vacinas. Com efeito as vacinas são medicamentos complexos com características únicas cuja vigilância necessita de abordagens metodológicas desenvolvidas para esse propósito. Do exposto se entende que, desde o desenvolvimento da farmacovigilância se tem procurado desenvolver novas metodologias que sejam concomitantes aos Sistemas de Notificação Espontânea que já existem. Neste trabalho propusemo-nos a desenvolver e testar um modelo de vigilância de reacções adversas a vacinas, baseado na auto-declaração pelo utente de eventos ocorridos após a vacinação e testar a capacidade de gerar sinais aplicando cálculos de desproporção a datamining. Para esse efeito foi constituída uma coorte não controlada de utentes vacinados em Centros de Saúde que foram seguidos durante quinze dias. A recolha de eventos adversos a vacinas foi efectuada pelos próprios utentes através de um diário de registo. Os dados recolhidos foram objecto de análise descritiva e análise de data-mining utilizando os cálculos Proportional Reporting Ratio e o Information Component. A metodologia utilizada permitiu gerar um corpo de evidência suficiente para a geração de sinais. Tendo sido gerados quatro sinais. No âmbito do data-mining a utilização do Information Component como método de geração de sinais parece aumentar a eficiência científica ao permitir reduzir o número de ocorrências até detecção de sinal. A informação reportada pelos utentes parece válida como indicador de sinais de reacções adversas não graves, o que permitiu o registo de eventos sem incluir o viés da avaliação da relação causal pelo notificador. Os principais eventos reportados foram eventos adversos locais (62,7%) e febre (31,4%).------------------------------------------ABSTRACT: The monitoring of undesirable effects following vaccination is complex. There are several confounding factors that can lead to merely temporal but spurious associations that can cause a change in the risk perception and a consequent generalized distrust about the safe use of vaccines. Indeed, vaccines are complex drugs with unique characteristics so that its monitoring requires specifically designed methodological approaches. From the above-cited it is understandable that since the development of Pharmacovigilance there has been a drive for the development of new methodologies that are concomitant with Spontaneous Reporting Systems already in place. We proposed to develop and test a new model for vaccine adverse reaction monitoring, based on self-report by users of events following vaccination and to test its capability to generate disproportionality signals applying quantitative methods of signal generation to data-mining. For that effect we set up an uncontrolled cohort of users vaccinated in Healthcare Centers,with a follow-up period of fifteen days. Adverse vaccine events we registered by the users themselves in a paper diary The data was analyzed using descriptive statistics and two quantitative methods of signal generation: Proportional Reporting Ratio and Information Component. themselves in a paper diary The data was analyzed using descriptive statistics and two quantitative methods of signal generation: Proportional Reporting Ratio and Information Component. The methodology we used allowed for the generation of a sufficient body of evidence for signal generation. Four signals were generated. Regarding the data-mining, the use of Information Component as a method for generating disproportionality signals seems to increase scientific efficiency by reducing the number of events needed to signal detection. The information reported by users seems valid as an indicator of non serious adverse vaccine reactions, allowing for the registry of events without the bias of the evaluation of the casual relation by the reporter. The main adverse events reported were injection site reactions (62,7%) and fever (31,4%).

Psychophysical estimation of the effective level of internal noise in the auditory system

This paper reviews a study to examine signal detection in the auditory system.

Robust classification of SAR imagery

In this work the G(A)(0) distribution is assumed as the universal model for amplitude Synthetic Aperture (SAR) imagery data under the Multiplicative Model. The observed data, therefore, is assumed to obey a G(A)(0) (alpha; gamma, n) law, where the parameter n is related to the speckle noise, and (alpha, gamma) are related to the ground truth, giving information about the background. Therefore, maps generated by the estimation of (alpha, gamma) in each coordinate can be used as the input for classification methods. Maximum likelihood estimators are derived and used to form estimated parameter maps. This estimation can be hampered by the presence of corner reflectors, man-made objects used to calibrate SAR images that produce large return values. In order to alleviate this contamination, robust (M) estimators are also derived for the universal model. Gaussian Maximum Likelihood classification is used to obtain maps using hard-to-deal-with simulated data, and the superiority of robust estimation is quantitatively assessed.

Type-1 error inflation in the traditional by-participant analysis to metamemory accuracy: a generalized mixed-effects model perspective

In order to examine metacognitive accuracy (i.e., the relationship between metacognitive judgment and memory performance), researchers often rely on by-participant analysis, where metacognitive accuracy (e.g., resolution, as measured by the gamma coefficient or signal detection measures) is computed for each participant and the computed values are entered into group-level statistical tests such as the t-test. In the current work, we argue that the by-participant analysis, regardless of the accuracy measurements used, would produce a substantial inflation of Type-1 error rates, when a random item effect is present. A mixed-effects model is proposed as a way to effectively address the issue, and our simulation studies examining Type-1 error rates indeed showed superior performance of mixed-effects model analysis as compared to the conventional by-participant analysis. We also present real data applications to illustrate further strengths of mixed-effects model analysis. Our findings imply that caution is needed when using the by-participant analysis, and recommend the mixed-effects model analysis.

A Time Efficient Optical Model for GATE Simulation of a LYSO Scintillation Matrix Used in PET Applications

A time efficient optical model is proposed for GATE simulation of a LYSO scintillation matrix coupled to a photomultiplier. The purpose is to avoid the excessively long computation time when activating the optical processes in GATE. The usefulness of the model is demonstrated by comparing the simulated and experimental energy spectra obtained with the dual planar head equipment for dosimetry with a positron emission tomograph ( DoPET). The procedure to apply the model is divided in two steps. Firstly, a simplified simulation of a single crystal element of DoPET is used to fit an analytic function that models the optical attenuation inside the crystal. In a second step, the model is employed to calculate the influence of this attenuation in the energy registered by the tomograph. The use of the proposed optical model is around three orders of magnitude faster than a GATE simulation with optical processes enabled. A good agreement was found between the experimental and simulated data using the optical model. The results indicate that optical interactions inside the crystal elements play an important role on the energy resolution and induce a considerable degradation of the spectra information acquired by DoPET. Finally, the same approach employed by the proposed optical model could be useful to simulate a scintillation matrix coupled to a photomultiplier using single or dual readout scheme.

Mixing vector construction for single channel semi-blind source separation using empirical mode decomposition

The Empirical Mode Decomposition (EMD) method is a commonly used method for solving the problem of single channel blind source separation (SCBSS) in signal processing. However, the mixing vector of SCBSS, which is the base of the EMD method, has not yet been effectively constructed. The mixing vector reflects the weights of original signal sources that form the single channel blind signal source. In this paper, we propose a novel method to construct a mixing vector for a single channel blind signal source to approximate the actual mixing vector in terms of keeping the same ratios between signal weights. The constructed mixing vector can be used to improve signal separations. Our method incorporates the adaptive filter, least square method, EMD method and signal source samples to construct the mixing vector. Experimental tests using audio signal evaluations were conducted and the results indicated that our method can improve the similar values of sources energy ratio from 0.2644 to 0.8366. This kind of recognition is very important in weak signal detection.

The use of mixed methods in drug discovery: integrating qualitative methods into clinical trials

Contemporary methods in clinical trials are pivoted around hypothesis confirmation, not generation. This is a problem for new drug discovery, since the pharmacokinetic or receptor profile of most novel agents do not link to pathophysiology, which is very poorly understood. Therefore, it is difficult to impute the therapeutic potential of a candidate agent. Most psychotropic agents were discovered serendipitously, either through careful clinical observation or by researchers finding unexpected associations in datasets. Methods that increase the ability to detect latent signals in data are needed. These include mixed methods that incorporate qualitative methods into randomized controlled trials.

This chapter proposes a methodology for the integration of mixed methods in clinical trials, fusing qualitative and quantitative methods, and presents an exemplar using this approach.

Mixed methods show potential for signal detection, hypothesis generation, and associations that may be otherwise undetected in traditional clinical trials.

Papel de sinais cromáticos na identificação de parceiros sexuais em sagüi comum (callithrix jacchus)

The literature concerning color vision shows a trichromatic advantage in detecting ripe fruits and young leaves, but there are contradictory results. There is also the suggestion of this type of vision being adapted to perceive socio-sexual signals. Indeed, Old World primates utilize the skin color of conspecifics as a factor of attraction. But in New World primates there is no record of a coloration signal in the body that can be utilized by other group members. The present study aims to: 1- test whether there is a relation between coloration of body regions and ovulatory cycle in female Callithrix jacchus; 2- Determine if this species uses visual signals to choose mates that are sexually receptive. We collected feces from six females during one month to quantify progesterone concentration by EIA. Body region coloration was measured using a portable spectrometer and modeled to obtain the quantum catch of each photoreceptor, the opponency channels and chromatic distance between the points in units of JND. We recorded the behavior of six males exposed to three pairs of females with a cycling and a non-cycling female in each pair using a transparent plexiglass apparatus. The color of different body regions presented a correlation between progesterone concentration and the yellow-blue and red-green visual axes, with the genitalia as the region showing the highest correlation. The visual axis more apt to see the color variations was the yellow-blue in dichromats, and in trichromats were the red-green to face, yellow-blue to abdomen and both chromatic axes to genitalia. There was no difference in the signal detectability between trichromats and dichromats, but the perception pattern differed between the phenotypes, with a better signal detection by the dichromat phenotype 562 and the trichromat phenotype 543/562. During the behavioral experiments males presented longer gaze duration in periods of experimental manipulation and gaze duration was always longer towards cycling females compared to non-cycling females. Male locomotion during experimental manipulation was greater than in the control only during the periovulatory period of the female, indicating greater excitement. The behavior of cycling females was more active than the behavior of the non-cycling ones regarding locomotion and touching of the plexiglass division of the apparatus. Male gaze duration to cycling females increased with decreasing progesterone concentration, but none of the coloration parameters was correlated to the mate preference exhibited. This coloration signal can transmit information to animals of the group about fertility of female. Different from the intense red of the genitalia swellings of Old World primates, marmoset female genitalia became more bluish-green in the fertile period. Males chose fertile females and were able to visually identify the periovulatory period of females. Choice is related to progesterone concentration, but our results do not show relation between coloration and mate preference. Maybe some behavioral measure is associated with the choice

Determinação de carbaril utilizando testes ELISA (Enzyme-linked immunosorbent assay) e CLAE com detecção por arranjo de diodos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)